RESUMO
Flotation is a simple, inexpensive, and versatile unit operation with a largely unexplored potential in biotechnology. There is a general lack of research concerning biotechnological applications in this area, especially in the recovery of fermentation products. Moreover, the few reports in the literature do not consider the modern concept of column flotation as practiced in the mineral industry. We report herein the application of column flotation for the recovery of a Bacillus stearothermophilus alpha-amylase expressed in Escherichia coli by the use of a food-grade polymer, (hydroxypropyl)methylcellulose (HPMC), and ammonium sulfate. First, the enzyme was removed from the liquid phase by partition to a salted-out HPMC phase. The enzyme-containing polymer flocs were then floated from the liquid. Recovery of active enzyme was as high as 90%, with throughput as high as 94 m3/(h.m2). The floatability of the enzyme from a periplasmic extract was higher than extracellular enzyme in the broth due to the presence of depressors of molecular weight lower than 10,000 in the broth.
Assuntos
Proteínas de Bactérias/isolamento & purificação , Biotecnologia/métodos , alfa-Amilases/isolamento & purificação , Sulfato de Amônio , Proteínas de Bactérias/genética , Escherichia coli/enzimologia , Escherichia coli/genética , Estudos de Avaliação como Assunto , Fermentação , Engenharia Genética/métodos , Geobacillus stearothermophilus/enzimologia , Geobacillus stearothermophilus/genética , Polímeros , alfa-Amilases/biossíntese , alfa-Amilases/genéticaRESUMO
A procedure for recovering Clostridium thermosulfurogenes produced beta-amylase from fermentation broth by partition was developed. The partition was achieved by addition of ammonium sulfate to an aqueous solution of the enzyme with (hydroxypropyl)methylcellulose. The beta-amylase-containing pellet formed upon centrifugation could be redissolved and the polymer recovered by a second salt addition. The process was not dependent on polymer/enzyme solution pH, but it was affected by temperature, polymer nominal molecular weight and loading, and fermentation carbon source. Unlike more traditional aqueous-phase partitions, such as poly(ethylene glycol)/dextran, the current approach appeared to be biospecific.
Assuntos
Técnicas de Química Analítica/métodos , Clostridium/enzimologia , Fermentação , beta-Amilase/isolamento & purificação , Celulose , Éteres , Géis , Derivados da Hipromelose , Metilcelulose/análogos & derivados , TemperaturaRESUMO
OBJECTIVE: To study effects of meditation on the shooting performance. METHODS: 25 elite shooters were investigated in an independent groups design. The results in standardised test shootings indoors and in ordinary competitions outdoors were assessed before and after regular meditation training for the experimental group. The experience of tension during the test shootings was self recorded on a visual analogue scale (VAS). RESULTS: The competition results in the outdoor season (1993), just after the meditation training period, compared with the results the previous season (1992), were better in the meditation group (P < 0.05). No significant difference between the groups was observed in the test shootings before and after the relaxation intervention. A significant association was shown between low tension and the results in the test shootings (correlation r = 0.42, P < 0.0001; Wilcoxon rank sum test, z = -3.36, P < 0.001); 18% (= r2) of the variance in performance was explained by tension. CONCLUSIONS: Meditation may enhance competitive shooting performance.